Oxidative phosphorylation, electron transport and active transport of amino acids are all membrane related phenomena which share common properties. Nevertheless, the basic properties of each process provide insight into their bioenergetic mechanisms. Some essential differences in these processes were observed with membrane vesicles differing in spatial orientation. The M. phlei system has been found to contain four different ATPases. All have been purified to homogeneity. Only one of the ATPases, that which is latent, also contains coupling factor activity. The various ATPases differ in their subunit structure. Attempts will be made to determine which of the subunits has binding sites for ADP and ATP and to reconstitute the other ATPases which do not have coupling factor activity. Evidence has been obtained which indicates that a proton gradient is not involved in either oxidative phosphorylation or active transport of amino acids. Preliminary evidence indicates that a transmembrane potential is the driving force for the uptake of amino acids. Further studies with fluorescent probes of ionophores will be carried out to follow the transmembrane potential. The active transport of proline appears to require a specific "port" for entry; however, efflux of this amino acid in contrast to other amino acids appear to occur by a different "port". Studies will be conducted to confirm this finding and to understand the efflux phenomenon, specially with regards to the bioenergetics. Cuprous ions have been shown to mediate transport in the absence of exogenous substrate. The Cu2 plus induces a conformational change in the carrier or transport protein from the sulfhydryl to disulfide state, whereas efflux occurs on the conversion of the disulfide state to the sulfhydryl configuration. The role of Cu2 ion and source of electron are under study. BIBLIOGRAPHIC REFERENCES: Alteration of Mycobacterium phlei Membrane Structure by Freezing and Thawing; Reversal by Heating. H. N. Aithal, Vijay K. Kalra and Arnold F. Brodie, Arch. Biochem. Biophys., 168, 122-132 ((1975) Effect of Phospholipase A on Active Transport of Amino Acids with Membrane Vesicles of Mycobacterium phlei. Rajendra Prasad, Vijay K. Kalra and Arnold F. Brodie, J. Biol. Chem., 250, 3699-3703 (1975).